1. Field of the Invention
The present invention relates to a lighting and/or signaling device, especially for automotive vehicles. It is in particular intended for position lamps, blinkers or stop lamps.
2. Description of the Related Art
In this sector, it is known to use luminous systems furnished with a light source, in general a light-emitting diode and a glass cover through which a light beam issuing from the source propagates. The glass cover serves both as protection for the luminous system and as complementary element of the bodyshell of the vehicle in relation to aerodynamic and esthetic aspects.
Strict rules embrace the possible choices of colors and intensities for the light beams of these devices. Thus, each function has a specific color, for example amber for the blinker, red for the stop lamp or the rear position lamp, or white for the reversing lamp and the front position lamp. Specific ranges allowed for these colors are defined in the international space. Other criteria also exist relating to the color of the glass cover of the device.
Moreover, it is known that constructors desire to distinguish themselves, especially with visually original elements, so as to be more easily identifiable with respect to competitors. A way of distinguishing oneself consists in having the glass cover of a first color and the beam emitted by the device in a second color different from the first. Thus, when the device is switched on, it emits a beam in a color corresponding to the function of the lamp, but when it is switched off, the color of the glass cover gives the lamp a different esthetic aspect. For example, it is possible to seek to have a lamp with a blinker function by emitting a beam issuing from a source of amber-tinted color and having a red colored glass cover for aesthetic reasons. Indeed, today, certain constructors desire to have the glass covers of the largest possible number of lamps of a similar, or indeed identical, color so as to make all the lamps appear uniform when they are switched off.
However, the drawback of these devices is that the color of the glass cover modifies the color of the light beam emitted by the light source. Indeed, the glass cover acts as a filter which allows through mainly the light whose wavelengths are close to its color. The deeper the color of the glass cover, the more significant the filtering.
Another problem stems from the fact that certain light sources, such as diodes, do not operate in the same manner at all temperatures. The higher the temperature of the diode, the more the color of the beam that it emits deviates toward a deeper color. Now, in normal use, the temperature of the diode reaches values of more than 80° C.
Furthermore, in certain countries standards exist regarding the color that the glass cover must have when the device is switched off. In particular, in the United States, red or amber glass covers must be sufficiently deeply colored. For cost reasons, it is important to provide a single device tailored to several countries, especially for the United States and Europe.